The enigma of soil nitrogen balance sheets has been discussed for over 40
years. Many reasons have been considered for the incomplete recovery of
15N applied to soils, including sampling uncertainty,
gaseous N losses from plants, and entrapment of soil gases. The entrapment of
soil gases has been well documented for rice paddy and marshy soils but little
or no work appears to have been done to determine entrapment in drained
pasture soils. In this study 15N-labelled nitrate was
applied to a soil core in a gas-tight glovebox. Water was applied, inducing
drainage, which was immediately collected. Dinitrogen and
N2O were determined in the flux through the soil
surface, and in the gases released into the glovebox as a result of irrigation
or physical destruction of the core. Other components of the N balance were
also measured, including soil inorganic-N and organic-N. Quantitative recovery
of the applied 15N was achieved when the experiment was
terminated 484 h after the 15N-labelled material was
applied. Nearly 23% of the 15N was recovered in
the glovebox atmosphere as N2 and
N2O due to diffusion from the base of the soil core,
convective flow after irrigation, and destructive soil sampling. This
15N would normally be unaccounted for using the sampling
methodology typically employed in 15N recovery
experiments.
Investigating Effects of Landfill Soil Gases on Landfill Elevated Subsurface Temperature
